INTERLEUKIN-1 INDUCES EXPRESSION OF THE HUMAN-IMMUNODEFICIENCY-VIRUS ALONE AND IN SYNERGY WITH INTERLEUKIN-6 IN CHRONICALLY INFECTED U1 CELLS - INHIBITION OF INDUCTIVE EFFECTS BY THE INTERLEUKIN-1 RECEPTOR ANTAGONIST

In the present study we have observed that interleukin (IL) 1alpha or IL-1beta directly induced expression of human immunodeficiency virus (HIV) in the latently infected human promonocytic cell line U1. In addition, IL-1 synergized with IL-6, but not with tumor necrosis factor, in the upregulation of virus expression in U1 cells as measured by accumulation of steady-state mRNAs and production of reverse transcriptase activity. The HIV inductive effect of IL-1 was blocked by transforming growth factor beta, anti-IL-1 antibodies, or monoclonal antibodies directed to the type 1, but not to the type 2, cell surface receptor for IL-1; the latter actually caused enhancement of the IL-1-mediated effect. Unlike tumor necrosis factor alpha, IL-1 either alone or in combination with IL-6 did not induce activation of the transcription activating factor NF-kappaB above the constitutive levels of unstimulated U1 cells. Finally, the IL-1 receptor antagonist effectively blocked IL-1-mediated direct and synergistic inductive effects on virus production. Thus, IL-1 may be an important mediator of HIV expression, and blocking of IL-1 expression and/or its effects may have a potential therapeutic role in the inhibition of HIV expression in infected individuals.